Melanosis of oral and genital mucosae (labial lentigo, lentiginosis of oral mucosa, genital lentiginosis) are benign melanotic macules characterized by single or often numerous lesions with a tendency to confluence.
Clinically, labial lentigo is usually situated on the lower lip and appears as a roundish, well circumscribed, light-brown macule. In contrast to the solitary labial lentigo, melanosis of the male and female genitalia is characterized by numerous, multifocal, relatively large (up to 2 cm), irregularly outlined macules with a variegated brownish pigmentation displaying a speckled pattern. Commonly they were regarded as having an atypical clinical appearance and at least close clinical follow-up examinations or, even better, punch biopsies are recommended.
A practical problem, especially when examining melanosis of the vulva and the penis, is the close working distance when using the conventional dermatoscope. Nevertheless, the dermoscopic features of melanosis on both oral and genital locations are rather characteristic, revealing diffuse pigmentation with a peculiar parallel pattern of partially linear and partially curvilinear light-brown to dark-brown streaks. Furthermore, based on our experience, melanoma-specific criteria such as atypical pigment network variations, irregular dots/globules and blue-whitish veil have not been found in benign labial and genital melanosis.